(a) Field of the Invention
The present invention relates to a liquid crystal display.
(b) Description of the Related Art
A liquid crystal display (“LCD”) includes a liquid crystal (“LC”) material injected between an upper panel and a lower panel and generates an electric field in the LC material to alter the orientation of the LC molecules, thereby inducing a change in the polarization of light passing through the LC material. The amount of light passing through polarizers is also changed according to the polarization to thereby display an image.
A uniform cell gap between the upper panel and the lower panel should be maintained, for which active spacers are used. Bead spacers or column spacers are used as the active spacers.
The bead spacers offer advantages including a simplified process and facilitate manufacture of an LCD, but since the bead spacers are floating in the LCD, the bead spacer move along with the LC material during the injection of the LC material into the LCD. Therefore, when the movement pressure and the movement distance are large, the alignment layer may be curved such that light leakage occurs.
On the other hand, since the column spacers are formed by a photolithography process, the column spacers can be selectively formed in necessary positions with fixed shapes. For such reasons, at present, the column spacers are used more often than the bead spacers.
However, the number of column spacers formed per unit area is smaller than that of the bead spacers. This problem, which is due to the photolithography process, is solved by adjusting the size of the column spacers.
When an external pressure (or impact) is exerted on an LCD with column spacers, the column spacers are not able to absorb the impact as well compared with bead spacers, so the column spacers damage electrodes under the spacers.
Also, since the column spacers are formed away from pixel electrodes, when the volume of LC material injected into an LCD is decreased at a low temperature of less than −20 degrees Celsius, the cell gap at the pixel electrodes is greatly reduced so that a difference between the cell gap at the pixel electrodes and the cell gap where the column spacers are formed is increased, which causes a phenomenon such as bubbles.